# resolving forces with questions refering to a bead suspended

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#1
Hi Guys,

I am in mechanics 1 and on the the various topics where you have to resolve forces. It's going well, however in the M1 Edexcel student book there a couple of questions that use a bead threaded through a string rather than a mass or particle.

Coming to them at first I didn't think these questions would be any different, but when they ask you for the tension in the string they ask for one tension value when the bead is suspended from two points at DIFFERENT angles. This will make the values different. The bead suspended with the horizontal makes a triangle, so there are still two tension points. In the questions where they use a mass they ask for two tension values, like AC and BC. I am confused about this! In these questions they do not give a mass value for the bead. This leads me to end up with three variables not being able to make simultaneous equations. They don't give any magnitude within in the triangle, just a force that acts outside of it.

For those that know the M1 Edexcel student book it is questions 5 and 6, exercise 4B.

If you want a diagram I will have to do it later, but here is the written question:

A smooth bead B is threaded on a light inextensible string. The ends of the string are attached to two fixed points A and C on the same horizontal level. The bead is held in equilibrium by a horizontal force of magnitude 2N acting parallel to CA. The sections of the string make angles of 60 degrees and 30 degrees with the horizontal.

Find the tension in the string and the mass of the bead?

Like I say I end up with 3 variables and am confused about the one value for the tension when there are two tension points.

0
5 years ago
#2
(Original post by Tygra)
Hi Guys,

This will make the values different. The bead suspended with the horizontal makes a triangle, so there are still two tension points. In the questions where they use a mass they ask for two tension values, like AC and BC.
You have one string so the tension is the same throughout
0
5 years ago
#3
(Original post by Tygra)
Hi Guys,

I am in mechanics 1 and on the the various topics where you have to resolve forces. It's going well, however in the M1 Edexcel student book there a couple of questions that use a bead threaded through a string rather than a mass or particle.

Coming to them at first I didn't think these questions would be any different, but when they ask you for the tension in the string they ask for one tension value when the bead is suspended from two points at DIFFERENT angles. This will make the values different. The bead suspended with the horizontal makes a triangle, so there are still two tension points. In the questions where they use a mass they ask for two tension values, like AC and BC. I am confused about this! In these questions they do not give a mass value for the bead. This leads me to end up with three variables not being able to make simultaneous equations. They don't give any magnitude within in the triangle, just a force that acts outside of it.

For those that know the M1 Edexcel student book it is questions 5 and 6, exercise 4B.

If you want a diagram I will have to do it later, but here is the written question:

A smooth bead B is threaded on a light inextensible string. The ends of the string are attached to two fixed points A and C on the same horizontal level. The bead is held in equilibrium by a horizontal force of magnitude 2N acting parallel to CA. The sections of the string make angles of 60 degrees and 30 degrees with the horizontal.

Find the tension in the string and the mass of the bead?

Like I say I end up with 3 variables and am confused about the one value for the tension when there are two tension points.

The tension in both sections of the string is constant, hence you have a horizontal equation involving T and the force of 2N.
You also have a vertical equation involving m and T.
Solve the horizontal first then substitute into the vertical to get m.
0
#4
(Original post by TenOfThem)
You have one string so the tension is the same throughout
Thanks guys, I now have the answer.

Sorry for undoubtedly assuming there would be two values.

Thankyou for helping me with my physics, ha ha ha ha ha.....
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